CN115448522B - System and method for purifying water quality of high-salt wastewater - Google Patents
System and method for purifying water quality of high-salt wastewater Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 75
- 239000002351 wastewater Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 33
- 239000007788 liquid Substances 0.000 claims abstract description 138
- 239000012528 membrane Substances 0.000 claims abstract description 109
- 229910001385 heavy metal Inorganic materials 0.000 claims abstract description 54
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 38
- 239000010881 fly ash Substances 0.000 claims abstract description 29
- 238000005374 membrane filtration Methods 0.000 claims abstract description 21
- 238000001704 evaporation Methods 0.000 claims abstract description 17
- 230000008020 evaporation Effects 0.000 claims abstract description 17
- 150000003839 salts Chemical class 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 16
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 15
- 239000002245 particle Substances 0.000 claims abstract description 6
- 238000005406 washing Methods 0.000 claims description 32
- 238000000926 separation method Methods 0.000 claims description 30
- 238000001728 nano-filtration Methods 0.000 claims description 27
- 238000004140 cleaning Methods 0.000 claims description 20
- 239000003814 drug Substances 0.000 claims description 17
- 238000001914 filtration Methods 0.000 claims description 14
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 12
- 238000001556 precipitation Methods 0.000 claims description 11
- 238000004062 sedimentation Methods 0.000 claims description 11
- 239000006228 supernatant Substances 0.000 claims description 8
- 239000004902 Softening Agent Substances 0.000 claims description 7
- 239000007791 liquid phase Substances 0.000 claims description 7
- 238000011010 flushing procedure Methods 0.000 claims description 6
- 238000000746 purification Methods 0.000 claims description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 6
- 239000002956 ash Substances 0.000 claims description 5
- 239000003153 chemical reaction reagent Substances 0.000 claims description 4
- 239000000084 colloidal system Substances 0.000 claims description 4
- 239000000428 dust Substances 0.000 claims description 4
- 239000013049 sediment Substances 0.000 claims description 4
- 239000002002 slurry Substances 0.000 claims description 4
- 239000007790 solid phase Substances 0.000 claims description 4
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 3
- 239000012445 acidic reagent Substances 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- 239000011268 mixed slurry Substances 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 3
- 235000011152 sodium sulphate Nutrition 0.000 claims description 3
- 230000006641 stabilisation Effects 0.000 claims description 3
- 238000011105 stabilization Methods 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 2
- 230000004907 flux Effects 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 238000004056 waste incineration Methods 0.000 claims 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 claims 1
- 239000012141 concentrate Substances 0.000 claims 1
- 230000003472 neutralizing effect Effects 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 5
- 229910052979 sodium sulfide Inorganic materials 0.000 abstract description 4
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 abstract description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 abstract description 3
- 230000002378 acidificating effect Effects 0.000 abstract description 2
- 239000011550 stock solution Substances 0.000 abstract description 2
- 102000005393 Sodium-Potassium-Exchanging ATPase Human genes 0.000 abstract 1
- 108010006431 Sodium-Potassium-Exchanging ATPase Proteins 0.000 abstract 1
- 239000000919 ceramic Substances 0.000 description 19
- 239000000243 solution Substances 0.000 description 16
- 230000001105 regulatory effect Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 238000010992 reflux Methods 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000011575 calcium Substances 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 3
- 235000019345 sodium thiosulphate Nutrition 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000012459 cleaning agent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000010840 domestic wastewater Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 230000003311 flocculating effect Effects 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- -1 high pH value Inorganic materials 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 230000004083 survival effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention discloses a system and a method for purifying water quality of high-salt wastewater. The system comprises a heavy metal removal unit, a softening treatment unit, a membrane filtration unit and a neutralization unit which are sequentially connected according to a process flow. On the basis of the system, high-salt wastewater generated after the fly ash is washed is conveyed to a heavy metal removal reactor through a transfer pump, sodium sulfide serving as a heavy metal capturing agent is added for heavy metal removal, then hardness is reduced through softening treatment, finally suspended particles in the wastewater, residual sulfate radicals and carbonate ions are sequentially removed through multistage membrane filtration, clear liquid after membrane treatment enters a neutralization reactor, pH is adjusted to 7.0 through adding acidic substances with a certain concentration, and stock solution meeting the water inlet requirement of an evaporation salt making process is obtained.
Description
Technical Field
The invention belongs to the technical field of high-salt wastewater treatment, in particular to a system and a method for purifying the water quality of high-salt wastewater, and particularly relates to a system and a method for purifying the water quality of high-salt wastewater after fly ash washing.
Background
The high-salt wastewater refers to discharged wastewater with total salt content higher than 1% from domestic wastewater and industrial wastewater, and contains higher Cl - ，SO 4 2- ，Na + ，Ca 2+ The plasma also contains organic matters such as glycerin and medium and low carbon chains. The high-salt wastewater is unfavorable for the survival of microorganisms because of high salt content, and is usually treated by adopting a physical technology of pretreatment, membrane concentration and evaporation.
The fly ash of the incineration of the household garbage contains CaO and SiO 2 ，Al 2 O 3 ，Na 2 O，K 2 Oxide such as O, etc., in the course of water washing, a large amount of substances such as potassium, sodium, calcium, chlorine, etc. are dissolved, so that the content of salt in the fly ash water washing liquid is high, and the fly ash water washing liquid is typical high-concentration inorganic high-salt wastewater. Secondly, the fly ash contains Pb, cd, zn, cu, cr and other heavy metals, and a certain amount of suspended matters remain in the water washing liquid in the solid-liquid separation process of the fly ash, so that the fly ash water washing liquid has the characteristics of high salt, high calcium, high pH value, heavy metal content, suspended matters and the like.
For the high-salt wastewater of fly ash washing liquid, the technology of pretreatment and evaporation is commonly adopted at present for treatment. The water quality of the water washing liquid is purified through pretreatment, the purposes of reducing hardness, removing heavy metals, reducing turbidity and regulating pH are achieved, the feed liquid meeting the requirement of evaporation water inlet is obtained, and then evaporation crystallization is carried out, so that byproduct salt is generated. Pretreatment technology of fly ash washing liquid comprises heavy metal removal, softening treatment, multistage filtration, neutralization and other multi-step treatment. Through the steps, the removal of heavy metals, hardness and suspended matters and the adjustment of pH can be sequentially realized, so that the requirement of water for the rear end is met.
The prior art Chinese patent (202011189399.4) discloses a method for purifying fly ash water washing liquid, which comprises the following steps: s1, enabling fly ash filtrate to enter a first washing reactor, and adding sodium carbonate solution into the first washing reactor; s2, the effluent of the first water washing reactor enters a second water washing reactor, and sodium thiosulfate is added into the second water washing reactor; s3, enabling the effluent of the second water washing reactor to enter a centrifugal machine; s4, enabling the effluent of the centrifugal machine to enter a first filter; s5, the effluent of the first filter enters a neutralization reactor; s6, the effluent of the neutralization reactor enters a second filter; s7, the effluent of the second filter enters an MVR feed box. According to the method for purifying the fly ash water washing liquid, the fly ash water washing liquid is treated by adopting sodium carbonate solution and sodium thiosulfate, and meanwhile, a stirring device is arranged in a reactor for stirring so as to remove substances such as calcium ions and heavy metals.
The prior art described above has achieved, to some extent, removal of heavy metals, hardness, suspended matter and pH adjustment for water purification of high-salt wastewater such as fly ash water wash. However, in the heavy metal and hardness removal process, the repeated use of the chemical and the consumption of a large amount of water cause resource waste and cost increase; secondly, with the separation capacity of current centrifuge, centrifuge effluent inevitably contains a certain amount of suspended solid, directly gets into the filter, very easily causes the jam of filter, needs a large amount of water to wash even change the filter media at this moment, and wash water can not be discharged the system that must return again outward, has both increased system pressure, has increased the cost of labor again.
Disclosure of Invention
Aiming at the defects of the prior art, the invention creatively provides a system and a method for purifying the water quality of high-salt wastewater. Firstly, the hardness remover is added in batches, so that the reaction time is prolonged, excessive addition is avoided, and the cost of the medicament is reduced. Secondly, a buffer pool is arranged between the two adding processes of the hardness removing agent, so that the residence time of the agent is prolonged, suspended matters in the high-salt wastewater are promoted to be settled, and the content of the suspended matters is reduced. Thirdly, the membrane filtration technology is adopted to treat the water washing liquid, so that suspended particles and colloid particles in the water washing liquid are further intercepted, and turbidity is effectively reduced. In addition, nanofiltration is adopted for filtration, sulfate radicals and carbonate radicals in the feed liquid are intercepted and returned to the front end for hardness removal, the adding cost of a hardness remover is reduced, and meanwhile, the stable operation of a subsequent evaporation crystallization section is ensured. Finally, membrane filtration is adopted to replace the original multi-medium filtration, and the membrane filtration device has the advantages of small occupied area, good filtration effect, high automation degree, medicament cost saving and the like.
In order to solve the technical problems, the invention provides the technical scheme that: a method for purifying water quality of high-salt wastewater comprises the following steps:
step (1): conveying the high-salt wastewater generated in the fly ash or kiln ash washing process section to a heavy metal removal reactor, and adding a heavy metal capturing agent (sodium sulfide, sodium thiosulfate or a special agent, preferably sodium sulfide) according to the heavy metal content in the wastewater in proportion to remove the heavy metal; in the step (1), the heavy metal capturing agent is added in an amount of 0.1-0.3kg/t of fly ash or kiln dust to ensure that heavy metals in the high-salt wastewater can be thoroughly removed.
The heavy metal content in the wastewater obtained in the step (1) is less than or equal to 50mg/L.
Step (2): conveying the high-salt wastewater in the step (1) to a softening reactor, and adding a softening agent (sodium sulfate, sodium carbonate and flocculating settling agent) with a certain mass concentration to reduce the hardness in the wastewater; the mixed slurry is concentrated and separated by a solid-liquid separation device, and the separated clear liquid enters a buffer sedimentation tank to further carry out sedimentation of suspended matters and water quality stabilization. And (3) delivering filter residues generated by the solid-liquid separation device in the step (2) to other systems for treatment, delivering the precipitated slurry generated by sedimentation in a buffer pool to a softening reactor, and delivering the precipitated slurry to the solid-liquid separation device again for treatment.
The addition amount of the softening agent in the step (2) is 50-200kg/t fly ash or kiln dust.
The hardness of the high-salt wastewater obtained in the step (2) is less than or equal to 200mg/L.
Step (3): and (3) conveying the supernatant of the buffer pool in the step (2) to a membrane feeding device for membrane filtration to remove suspended matters and colloid particles in the wastewater, transferring the filtered feed liquid into a supernatant storage device, then, entering a nanofiltration device to remove divalent ions in the wastewater, and enabling the effluent passing through the nanofiltration device to enter a neutralization unit.
And (3) circularly concentrating the feed liquid in the step (3) in the membrane component through a circulating pump. In the step (3), the membrane filter device comprises a back flushing mode and a cleaning mode besides a normal filter mode, and is provided with the back flushing and cleaning device. When the filter mode is adopted, the high-salt wastewater of the membrane feeding device in the step (3) is pumped into the membrane assembly through the feeding pump, and after membrane filtration, the concentrated solution flows back to the membrane feeding device to carry out material balance, and new feed liquid is continuously supplemented to maintain the liquid level of the membrane feeding device; the clear liquid enters a clear liquid storage device; when the membrane is in a backflushing mode, the filtering mode in the step (3) operates normally, compressed air in the backflushing device enters the membrane from a clear liquid outlet of the membrane assembly, backflushing is carried out on the membrane holes, and the membrane flux is maintained; and (3) after the membrane in the step (3) operates for a certain time, cleaning regularly, when the membrane is in a cleaning mode, the filtering mode is closed, the medicament in the cleaning device enters the membrane component through the dosing pump to clean the membrane, and the cleaned concentrated liquid and clear liquid simultaneously return to the cleaning device to be cleaned again. And (3) refluxing the membrane filtration concentrated solution to a membrane feeding device, and returning to a softening unit for solid-liquid separation after the concentrated concentration is achieved. And (3) after the membrane stops running in the step (3), emptying is carried out through an emptying port, and emptying liquid is transferred to the water quality purification emergency device. And (3) refluxing the concentrated solution of the nanofiltration membrane in the step (3) to a softening unit, and carrying out hard removal again by utilizing carbonate ions and sulfate ions trapped in the concentrated solution.
Step (4): and (3) conveying the clear liquid filtered by the nanofiltration membrane in the step (3) to a neutralization reactor for neutralization to obtain the water washing liquid meeting the water inlet requirement of evaporation salt preparation.
Adding an acidic reagent (hydrochloric acid) with a certain concentration into the neutralization reactor in the step (4), and adjusting the pH to 6.5-7.5, wherein the reagent addition amount is set according to the water inflow and the original pH of the water washing liquid;
the water discharged from the neutralization reactor in the step (4) is the water fed in the evaporation salt making process.
The second technical scheme of the invention is a system for purifying the water quality of high-salt wastewater, which comprises a heavy metal removal unit, a softening treatment unit, a membrane filtration unit and a neutralization unit which are sequentially connected according to a process flow.
The heavy metal removal unit comprises a heavy metal removal reactor. The feed liquid inlet of the heavy metal removal reactor is the inlet of a water quality purification unit of high-salt wastewater (fly ash water washing liquid), and the dosing port of the heavy metal removal reactor is the heavy metal capturing agent adding port; the outlet of the heavy metal removal reactor is connected with the inlet of the softening reactor of the softening treatment unit.
The softening treatment unit comprises a softening reactor, a solid-liquid separation device and a buffer precipitation device which are connected in sequence. The liquid inlet of the softening reactor is connected with the outlet of the heavy metal removal reactor, the medicine adding port of the softening reactor is a softening agent adding port, the outlet of the softening reactor is connected with the inlet of the solid-liquid separation device, the liquid phase outlet of the solid-liquid separation device is connected with the inlet of the buffer precipitation device, and the liquid phase outlet of the buffer precipitation device is connected with the inlet of the membrane feeding device of the membrane filtration unit; the solid phase of the solid-liquid separation device enters other systems; and a solid phase outlet of the buffer precipitation device is connected with an inlet of the softening reactor.
The membrane filtration unit comprises a membrane feeding device, a membrane component, a clear liquid storage device and a nanofiltration device which are connected in sequence. The feed liquid inlet of the membrane feeding device is connected with the liquid phase outlet of the buffer sedimentation device of the softening treatment unit, the feed liquid outlet of the membrane feeding device is connected with the feed liquid inlet of the membrane assembly, the concentrated liquid outlet of the membrane assembly is connected with the concentrated liquid inlet of the membrane feeding device, the concentrated solution outlet of the membrane feeding device is connected with the concentrated solution reflux port of the softening reactor of the softening unit, and the clear solution outlet of the membrane component is connected with the feed solution inlet of the clear solution storage device.
The liquid outlet of the clear liquid storage device is connected with the liquid inlet of the nanofiltration membrane, the concentrated liquid outlet of the nanofiltration membrane is connected with the concentrated liquid reflux port of the softening reactor of the softening unit, and the clear liquid outlet of the nanofiltration membrane is connected with the inlet of the neutralization reactor of the neutralization unit.
The neutralization unit comprises a neutralization reactor, and an inlet of the neutralization reactor is connected with a clear liquid outlet of a nanofiltration membrane of the membrane filtration unit; the medicine adding port of the neutralization reactor is a medicine adding port; the outlet of the neutralization reactor is the water outlet which meets the evaporation salt making process.
Advantageous effects
Compared with the prior art, the invention has the following outstanding technical effects:
firstly, the hardness remover is added in batches, so that the reaction time is prolonged, excessive addition is avoided, and the cost of the medicament is reduced.
Secondly, a buffer pool is arranged behind the liquid phase of the first solid-liquid separation, so that the residence time and the action time of the medicament are increased, suspended matters in the high-salt wastewater are promoted to be settled, and the content of the suspended matters is reduced.
Thirdly, the membrane filtration technology is adopted to treat the water washing liquid, so that suspended matters in the liquid are further trapped. Meanwhile, the ceramic membrane system has small occupied area and good filtering effect, and only the membrane system needs to be periodically washed by adding medicine, and the online operation can be realized by washing, so that the degree of automation is high, and the cost is saved.
And finally, filtering by nanofiltration, intercepting and returning excessive sulfate radical and carbonate radical in the feed liquid to the front end for reuse, reducing the cost of the medicament, and simultaneously ensuring the stable operation of the subsequent evaporation crystallization section.
Drawings
Figure 1 is a basic flow chart of the present invention.
Figure 2 is a flow chart of the method of the present invention.
Figure 3 is a process flow diagram of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and examples.
Example 1
The system for purifying water quality of high-salt wastewater in this embodiment, as shown in fig. 3, includes a heavy metal removal unit, a softening treatment unit, a membrane filtration unit and a neutralization unit.
In an embodiment, there is also provided a method for purifying wastewater quality by using the system for purifying high-salt wastewater quality as described above, as shown in fig. 2, including:
step (1): and (3) conveying the high-salt wastewater generated after the fly ash is washed to a heavy metal removal reactor through a transfer pump, adding 0.3kg/t of sodium sulfide serving as a heavy metal capturing agent of the fly ash, and removing heavy metal to obtain high-salt wastewater with heavy metal content of 30 mg/L.
Step (2): and (3) carrying out water softening treatment on the high-salt wastewater subjected to heavy metal removal reaction, removing hardness, further settling in a buffer water tank, and homogenizing.
Step (2-1): and (3) conveying the high-salt wastewater subjected to heavy metal removal reaction in the step (1) to a softening reactor, adding 120kg/t sodium carbonate agent of fly ash, and removing hardness.
Step (2-2): and conveying the feed liquid subjected to the dosing treatment to a solid-liquid separation device for mud-water separation to obtain clear liquid with the solid content of 0.8% and wet mud with the water content of 39%.
Step (2-3): the clear liquid after solid-liquid separation enters a buffer pool, secondary precipitation is carried out on fine suspended matters in the clear liquid, the functions of adjusting water quantity and homogenizing are achieved, and supernatant with the hardness of 120mg/L and sedimentation sediment are obtained through secondary sedimentation.
Step (2-4): supernatant in the buffer pool enters the next unit, settled sediment returns to a softening reactor of the softening treatment unit and enters the solid-liquid separation device again for mud-water separation.
Step (2-5): and conveying the wet sludge after solid-liquid separation to a drying system for moisture removal, and then performing innocent treatment.
Step (3): and (3) performing turbidity removal treatment on the supernatant obtained in the step (2-4) through a ceramic membrane, reducing suspended matters of high-salt wastewater, and removing residual sulfate radical and carbonate ions in the wastewater through a nanofiltration membrane.
Step (3-1): supernatant in the buffer pool overflows to a membrane feeding device, is pumped to a cartridge filter through a discharge pump, and then enters a ceramic membrane tube 1 and a ceramic membrane tube 2 for filtering.
Step (3-2): the filtered concentrated solution is internally circulated in the ceramic membrane tube 1 and the ceramic membrane tube 2 through a circulating pump, and the membrane component can also adopt a coiled or tubular organic membrane.
Step (3-3): when the solid content of the concentrated solution in the ceramic membrane reaches 25%, a concentrated solution reflux valve is opened, the concentrated solution is returned to the membrane feeding device, and the feed liquid is supplemented into the ceramic membrane.
Step (3-4): the filtered clear liquid enters a clear liquid storage device through a clear liquid valve control and then sequentially enters a nanofiltration membrane for filtration.
Step (3-5): and returning the concentrated solution filtered by the nanofiltration membrane to a softening reactor of the softening unit, and carrying out hard removal again by using the residual medicament in the concentrated solution.
Step (3-6): and (3) allowing the clear liquid filtered by the nanofiltration membrane to enter a neutralization unit, and regulating the pH.
Further, a feeding valve is arranged on a pipeline from the membrane feeding device to the ceramic membrane, and the feeding frequency of the ceramic membrane is controlled.
Furthermore, flow meters are respectively arranged on the feed pipe, the thick liquid return pipe and the clear liquid pipe to monitor the flow of the feed water, the thick liquid and the clear liquid.
Further, a pressure sensor and a pressure regulating valve are provided, and when the sensor detects that the pressure in the ceramic film is higher than the critical pressure (0.6 MPa), the pressure is regulated by the pressure regulating valve.
Further, a temperature sensor is arranged, the temperature of the feed liquid in the whole ceramic membrane is monitored, and the critical temperature of the ceramic membrane is 70 ℃.
Further, an exhaust pipe and an exhaust valve are arranged on the ceramic membrane pipe and are discharged to the membrane feeding device, so that the air pressure in the membrane is prevented from affecting feeding.
Further, a backflushing device is arranged, compressed air is stored in the backflushing device through a backflushing air inlet valve, when backflushing is needed, the backflushing valve is opened, the compressed air enters from a clear liquid port to backflush the membrane hole, and the membrane hole is prevented from being blocked by feed liquid. The back flushing can be automatically operated on line, and the back flushing is automatically carried out after the fixed time is set.
Further, a cleaning device is arranged, a reagent (cleaning agent such as acid, alkali and the like) with a certain concentration is added into the cleaning tank, after the ceramic membrane runs for a certain time, the feeding valve is closed, the cleaning pump and the cleaning valve are opened for cleaning, and the feed liquid (concentrated liquid and clear liquid) after the ceramic membrane is cleaned returns to the membrane cleaning device for cleaning again. And after the cleaning is finished, discharging the cleaning liquid into an emergency device for treatment.
Further, a discharge valve is arranged below the membrane feeding device, the ceramic membrane and the backflushing device, when the feed liquid in the membrane feeding tank is concentrated to a certain concentration, a blow-off valve of the feeding device is opened, and the concentrated liquid returns to the softening reactor and then enters the solid-liquid separation device for mud-water separation. When the ceramic membrane system is stopped, the feeding device, the ceramic membrane and the recoil device blow-down valve are simultaneously opened to empty the device.
Step (4): the clear liquid of the nanofiltration membrane enters a neutralization reactor, and the pH value is regulated to 7.0 by adding acidic substances (hydrochloric acid and the like) with a certain concentration, so as to obtain the stock solution meeting the water inlet requirement of the evaporation salt making process.
Examples 2 to 7
The other steps of examples 2 to 7 are substantially the same as those of example 1 except that the key process parameters of examples 2 to 7 are different from the following table.
Examples 2-7 parameter Table
The invention solves the problems of large dosage of medicament, incomplete removal of suspended matters and easy blockage in the filtering process in the purification process of the fly ash water washing liquid by organically combining treatment processes such as heavy metal removal, softening treatment, membrane filtration and the like, realizes the removal of heavy metal, hardness, turbidity and SS in the water washing liquid, and ensures the stable operation of an evaporation salt making unit and the quality of crystallized salt.
Claims (7)
1. The system for purifying the water quality of the high-salt wastewater is characterized by comprising a heavy metal removing unit, a softening unit, a membrane filtering unit and a neutralizing unit which are connected in sequence according to a process flow;
the heavy metal removal unit comprises a heavy metal removal reactor, a feed liquid inlet of the heavy metal removal reactor is a high-salt wastewater water quality purification unit inlet, a heavy metal removal reactor dosing inlet is a heavy metal capturing agent adding port, and an outlet of the heavy metal removal reactor is connected with a softening reactor inlet of the softening treatment unit;
the softening treatment unit comprises a softening reactor, a solid-liquid separation device and a buffer precipitation device which are sequentially connected, wherein a feed liquid inlet of the softening reactor is connected with an outlet of a heavy metal removal reactor, a medicine adding port of the softening reactor is a softening medicine adding port, an outlet of the softening reactor is connected with an inlet of the solid-liquid separation device, a liquid phase outlet of the solid-liquid separation device is connected with an inlet of the buffer precipitation device, a liquid phase outlet of the buffer precipitation device is connected with a membrane feeding device inlet of the membrane filtration unit, a solid phase of the solid-liquid separation device enters other systems, and a solid phase outlet of the buffer precipitation device is connected with an inlet of the softening reactor;
the membrane filtration unit comprises a membrane feeding device, a membrane assembly, a clear liquid storage device and a nanofiltration device which are sequentially connected, wherein a feed liquid inlet of the membrane feeding device is connected with a liquid phase outlet of a buffer sedimentation device of the softening treatment unit, a feed liquid outlet of the membrane feeding device is connected with a feed liquid inlet of the membrane assembly, a concentrated liquid outlet of the membrane assembly is connected with a concentrated liquid inlet of the membrane feeding device, a clear liquid outlet of the membrane assembly is connected with a feed liquid inlet of the clear liquid storage device, a feed liquid outlet of the clear liquid storage device is connected with a feed liquid inlet of the nanofiltration membrane, and a clear liquid outlet of the nanofiltration membrane is connected with an inlet of a neutralization reactor of the neutralization unit;
the neutralization unit comprises a neutralization reactor, wherein an inlet of the neutralization reactor is connected with a clear liquid outlet of a nanofiltration membrane of the membrane filtration unit, a medicine adding port of the neutralization reactor is a medicine adding port, and an outlet of the neutralization reactor is a water outlet which meets the evaporation salt making process;
(1) Introducing the high-salt wastewater obtained after the waste incineration fly ash or kiln ash is washed into a heavy metal removal reactor, and removing heavy metal by adding a heavy metal capturing agent, wherein the adding amount of the heavy metal capturing agent is 0.1-0.3kg/t of fly ash or kiln ash, so that the heavy metal content is less than or equal to 50mg/L;
(2) The high-salt wastewater obtained in the step (1) passes through a softening reactor, and softening agents including sodium carbonate and sodium sulfate are added to reduce the hardness; wherein the addition amount of the softening agent is 50-200kg/t fly ash or kiln dust, and the hardness of the obtained high-salt wastewater is less than or equal to 200mg/L;
concentrating and separating the mixed slurry by a solid-liquid separation device, and allowing the separated clear liquid to enter a buffer pool for precipitation, so as to further perform sedimentation of suspended matters and water stabilization;
the filter residues generated by the solid-liquid separation device in the step (2) are sent to other systems for treatment, the sediment slurry generated by sedimentation in the buffer pool is returned to the softening reactor and is sent to the solid-liquid separation device again for treatment;
(3) Delivering the supernatant of the buffer pool in the step (2) to a membrane feeding device for membrane filtration to remove suspended matters and colloid particles in the wastewater, transferring the filtered feed liquid into a clear liquid storage device, then delivering the clear liquid into a nanofiltration device to remove divalent ions in the wastewater, and delivering the effluent through the nanofiltration device into a neutralization unit;
(4) Conveying the clear liquid filtered by the nanofiltration membrane in the step (3) to a neutralization reactor for neutralization to obtain water washing liquid meeting the water inlet requirement of evaporation salt preparation;
adding an acidic reagent into the neutralization reactor in the step (4), and adjusting the pH to 6.5-7.5, wherein the reagent addition amount is set according to the water inflow and the original pH of the water washing liquid;
the water discharged from the neutralization reactor in the step (4) is the water fed in the evaporation salt making process.
2. The method for purifying water quality by using the high-salt wastewater as claimed in claim 1, which is characterized by comprising the following steps:
(1) Introducing the high-salt wastewater obtained after the waste incineration fly ash or kiln ash is washed into a heavy metal removal reactor, and removing heavy metal by adding a heavy metal capturing agent, wherein the adding amount of the heavy metal capturing agent is 0.1-0.3kg/t of fly ash or kiln ash, so that the heavy metal content is less than or equal to 50mg/L;
(2) The high-salt wastewater obtained in the step (1) passes through a softening reactor, and softening agents including sodium carbonate and sodium sulfate are added to reduce the hardness; wherein the addition amount of the softening agent is 50-200kg/t fly ash or kiln dust, and the hardness of the obtained high-salt wastewater is less than or equal to 200mg/L;
concentrating and separating the mixed slurry by a solid-liquid separation device, and allowing the separated clear liquid to enter a buffer pool for precipitation, so as to further perform sedimentation of suspended matters and water stabilization;
the filter residues generated by the solid-liquid separation device in the step (2) are sent to other systems for treatment, the sediment slurry generated by sedimentation in the buffer pool is returned to the softening reactor and is sent to the solid-liquid separation device again for treatment;
(3) Delivering the supernatant of the buffer pool in the step (2) to a membrane feeding device for membrane filtration to remove suspended matters and colloid particles in the wastewater, transferring the filtered feed liquid into a clear liquid storage device, then delivering the clear liquid into a nanofiltration device to remove divalent ions in the wastewater, and delivering the effluent through the nanofiltration device into a neutralization unit;
(4) Conveying the clear liquid filtered by the nanofiltration membrane in the step (3) to a neutralization reactor for neutralization to obtain water washing liquid meeting the water inlet requirement of evaporation salt preparation;
adding an acidic reagent into the neutralization reactor in the step (4), and adjusting the pH to 6.5-7.5, wherein the reagent addition amount is set according to the water inflow and the original pH of the water washing liquid;
the water discharged from the neutralization reactor in the step (4) is the water fed in the evaporation salt making process.
3. The method according to claim 2, wherein the feed liquid in the step (3) is circularly concentrated in the membrane module by a circulating pump: in the step (3), the membrane filter device is provided with a back flushing mode and a cleaning mode besides a normal filter mode, and is provided with a back flushing and cleaning device;
when the filter mode is adopted, the high-salt wastewater of the membrane feeding device in the step (3) is pumped into the membrane assembly through the feeding pump, the concentrated solution is filtered through the membrane and flows back to the membrane feeding device for material balance, new feed liquid is continuously supplemented to maintain the liquid level of the membrane feeding device, and clear liquid enters the clear liquid storage device;
when the membrane is in the backflushing mode, the filtering mode in the step (3) operates normally, compressed air in the backflushing device enters the membrane from a clear liquid outlet of the membrane assembly, backflushing is carried out on the membrane holes, and the membrane flux is maintained.
4. The method according to claim 2, wherein the membranes in step (3) are cleaned periodically after running for a certain period of time, and when the membranes are in a cleaning mode and the filtration mode is closed, the medicament in the cleaning device enters the membrane assembly through the dosing pump to clean the membranes, and the cleaned concentrated liquid and clear liquid simultaneously return to the cleaning device to be cleaned again.
5. The method according to claim 2, wherein the membrane filtration concentrate in the step (3) is returned to the membrane feeding device, and returned to the softening unit for solid-liquid separation after reaching the concentration.
6. The method of claim 2, wherein after the membrane is stopped in step (3), the membrane is evacuated through an evacuation port, and the evacuation liquid is transferred to a water purification emergency device.
7. The method according to claim 2, wherein the concentrated solution of the nanofiltration membrane in the step (3) is refluxed to a softening unit, and the concentrated solution is used for re-hardening by utilizing carbonate and sulfate ions trapped in the concentrated solution.
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